The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 04, 1984
Filed:
Mar. 10, 1982
Hitachi, Ltd., Tokyo, JP;
Abstract
In a converter comprising gate turn-off thyristors, a current at an A.C. part of the converter is detected and a polarity of the detected current and a magnitude of the detected current is checked to determine if it is below a holding current level for maintaining the gate turn-off thyristors on. If the detected current is below the holding current level, a pulse width modulated signal is produced as a gate signal. If the detected level is above the holding current level, a short duration pulse synchronized with a rise and a fall of the pulse width modulated signal is produced as the gate signal. The gate signal is supplied to only those of the gate turn-off thyristors which correspond to the polarity of the detected current.